It works only if you truly are willing to walk away…and then refuse to bend when they try to put you off or change the terms. Stay civil, do not let any emotion in. You are on a mission, Marine!
Fantastic advice. My dad is a skilled car buyer and on one particular occasion, spend two grueling hours dinkering with a used car saleman over a junky but good-running truck. He walked out at least twice and kept escalating up to the manager before getting the price down from $2300 to around $400.